The present application for continuing K24 support is a logical extension of productive mentorship and research progress during the prior cycle of funding, during which three K08 mentees achieved fundable R01 priority scores; the Cleveland Clinic Lerner College of Medicine (CCLCM) research program was integrated into the PI's mentorship activities; laboratory post-docs achieved independent funding and/or faculty positions; and several external mentees competed successfully for funding. We now seek support to expand mentorship interactions with the CCLCM through membership on the Research Education Committee (REC), which sets research policy and develops tools to assist research mentors with their mission to graduate clinician-scientists from the CCLCM. Integral to this activity is a structured evaluation process during which the PI will meet regularly with Dr. Christine Taylor, Director of Faculty Development for the Cleveland Clinic, and discuss student feedback, which will be used to develop enhance research mentoring at the CCLCM. The present application also benefits from establishment of the NIH/NCRR-funded Case Western Reserve University School of Medicine (CWRU-SOM)/Cleveland Clinic Clinical and Translational Science Collaborative (CTSC), which includes a clinician-scientist KL2 mentored post-doctoral program. The applicant will join the Multidisciplinary Advisory Committee (MAC) for the CTSC, participating in selection and mentorship of KL2 clinician-scientist awardees. Together, these activities represent a significant new direction for the applicant within the Cleveland Clinic's research education program. The research proposal also takes advantage of the PI's development of a novel flow-enhanced in-vitro blood-brain barrier (BBB) model, which will be used to examine how chemokine receptors are modulated by leukocyte-endothelial interactions under flow. These experiments incorporate chemokines and a brain microvascular endothelial cell monolayer, and assays are conducted in a modified chemotaxis chamber developed specifically for this research. Specific research aims are: Aim 1: To define how chemokine CXCL12 signals selectively to monocytes to promote transmigration of lymphocytes. Aim 2: To establish how luminal 'arrest' chemokines modulate chemokine receptor expression on transmigrated cells. Aim 3: To determine how abluminal 'transmigration' chemokines regulate chemokine receptor expression on transmigrated cells. Students and post-docs participate in both the basic and clinical/translational elements of research using this novel system and use their own data to address which chemokine receptors represent logical targets for therapeutic intervention in neurological disease.